Seatback recliner mechanism

ABSTRACT

A hinge fitting for a reclining vehicle seat structure comprises a fixed support bracket, a seatback member, a locking member, and a lock actuating mechanism. The lock actuating mechanism includes a cam that interacts with the locking member to urge the locking member into locking and unlocking positions. Proper positioning of the cam and locking member directs a force applied to the seatback that maintains a locking position. Alignment means is provided ensuring a proper positional relationship between the cam and locking member to correctly direct the applied force. The cam is operated through a linkage assembly which contains a biasing spring that is entirely shielded from user contact. Construction of the hinge fitting is facilitated by manufacturing a universal hinge fitting capable of assembly in multiple configurations.

This application is a divisional of application Ser. No. 08/132,663,filed Oct. 6, 1993, now U.S. Pat. No. 5,433,507.

BACKGROUND

The present invention relates generally to hinge fittings for areclining vehicle seat structure and, more particularly, to a noveldesign and arrangement of the lock actuating mechanism for such a seatstructure.

Vehicle seats are generally designed for simultaneous forward andrearward adjustment of the seat and seatback members. Other adjustments(e.g., vertical or tilt) of both seat and seatback members, as a unit,may or may not be provided. However, it is often desirable to allow foradjustment of the seatback member, relative to the seat member, toprovide an adjustable reclining seatback. Hinge fittings which providefor this type of adjustment normally include a fixed support bracketmounted to the vehicle seat, a seatback support member which isadjustable through a range of reclining positions and which is attachedto the seatback and pivotally connected to all of the following: thefixed support bracket, a locking member to lock the seatback support atvarious inclined positions, and a lock actuating mechanism for engagingor disengaging the locking member.

Examples of hinge fittings of this general type are shown in U.S. Pat.No. 3,999,247 to Cremer and U.S. Pat. No. 3,973,288 to Pickles.Refinements related to the specific shape and dimensionalcharacteristics of the lock actuating mechanism, which in this patentincludes a cam and a pawl, are shown in U.S. Pat. No. 4,223,947, also toCremer, and U.S. Pat. No. 4,875,735 to Moyer and the Applicant. Otherrefinements have been made to the pivot arm assembly and linkage whichcontrols the lock actuating mechanism, like those found in U.S. Pat. No.4,875,735 to Moyer and the Applicant and U.S. Pat. No. 4,872,726 toWhite.

Problems with hinge fittings of the above-referenced types relate toundesired contact between the linkage of the pivot arm assembly andother components in the hinge fitting. This occurs during adjustment ofthe level of reclination which naturally requires movement of the hingefitting mechanisms. Also, undesired contact can occur between thelinkage and both the seat to which the hinge fitting is attached, aswell as the user. Specifically, placement of the linkage connecting rodand the corresponding biasing spring, collectively the linkage assembly,in previously designed hinge fittings left portions of the linkageassembly, and in particular the biasing spring, exposed to externalsurroundings. During adjustment of the seat, when the user's hand isnear the linkage assembly, movement of the linkage assembly sometimescaused damage to the seat itself and posed a threat of injury to theuser.

Another problem with prior art hinge fittings was the difficulty ofassuring that the assembled fitting would withstand sufficient torquewhen in the locked position without releasing. This problem isaccentuated by the stacking of tolerances effect that occurs whenassembling the fitting. Although one previous prior fitting determineswhether the stacked tolerances were within the acceptable range bywhether an alignment dot appeared in the upper or lower half of a viewwindow defined by a sandwich plate, this approach has significantlimitations.

Also, hinge fittings are used in commercial applications where a certainmaximum reclining position is desired. Specifically, most applicationsutilize hinges having a maximum angle of reclination of 30° or 45°.Accordingly, manufacturers currently manufacture and warehouse hingeshaving a maximum angle of reclination of 30° and hinges having a maximumangle of reclination of 45°.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a hinge fitting for areclining vehicle seat which has a linkage structure that will notadversely affect the hinge fitting itself or the vehicle seat, and willalso not cause injury to the operator.

Another aspect of the invention is a hinge fitting for a recliningvehicle seat which can quickly and accurately be checked for properalignment of the lock actuating mechanism to ensure that usage of thereclining seat will not result in an unwanted disengagement of themechanism.

A further aspect of this invention is a hinge fitting for a recliningvehicle seat which can be assembled to provide either of two maximumreclination angles commonly used by consumers.

Desirably, a hinge fitting of the present invention includes a fixedsupport bracket, a seatback support member pivotally connected to thefixed support bracket and adjustable through a range of inclinedpositions, a locking member pivotally connected to the support bracketfor locking the seatback support member in a desired position, and alock actuating mechanism for moving the locking member to a locking andan unlocking position. The lock actuating mechanism includes a cam whichengages the locking member at an engagement point, when the lockingmember is in the locking position, such that a force applied to the camby the locking member at the engagement point tends to pivot the cam ina direction which causes the cam to urge the locking member toward thelocking position.

Advantageously, to ensure that the cam and the locking member are in thecorrect positional relationship which will direct this force properly,alignment markings are placed directly on both the cam and the lockingmember. Importantly, these markings extend substantially to the edgeformed between the outwardly facing surfaces of the cam and cammingsurface and to the edge formed by the outwardly facing surfaces of thelocking member and the locking surface which mates with the cammingsurface. Accordingly, there is little risk that although the housing andthe cam are aligned, the cam and the pawl are not. Likewise, thesemarkings can be seen before the unit is fully assembled, facilitating aquick correction of any problem. However, desirably, a view window isprovided in the seat support bracket to enable the tolerances to bechecked once the unit is fully assembled to determine whether toleranceproblems have arisen as a result of the remainder of the assemblyprocess.

The locking mechanism is controlled via a linkage member and anoperating handle. The linkage member and associated biasing spring areprotected during movement from interference with the hinge fitting,portions of the seat, and from the actual reclining seatback user. Thepreferred embodiment of the invention is constructed in a universalconfiguration which allows for assembly in one of two formats dependingon the level of maximum inclination for the vehicle seat.

These and other features of the present invention will become more fullyapparent from the following description and dependent claims taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is an exploded perspective view of a first hinge fitting, asexists in the prior art, having fixed support sections for mounting therelease handle and linking the handle to an actuator assembly.

FIG. 1b is a sectional view of the hinge fitting shown in FIG. 1adepicting the internal components.

FIG. 2 is an exploded perspective view of a second hinge fitting, asexists in the prior art, having fixed support sections for mounting therelease handle and linking the handle to an actuator assembly.

FIG. 3 is an exploded perspective view of a hinge fitting in accordancewith the present invention.

FIG. 4 is a sectional view of a hinge fitting in accordance with thepresent invention depicting the internal components and an operationalforce exerted upon the internal components.

FIG. 5 is a bottom view of the hinge fitting of FIG. 4.

FIG. 6 is an enlarged partial sectional view of the hinge fitting ofFIG. 4 depicting the interaction between the cam and the lockingmechanism.

FIG. 7 is a side elevation of the hinge fitting of FIG. 4 depicting afirst configuration allowing a maximum reclining position of 45 degrees.

FIG. 8 is a side elevation of the hinge fitting of FIG. 4 depicting asecond configuration allowing a maximum reclining position of 30degrees.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to FIG. 1a, there is illustrated a prior art hinge fittingfor a reclining vehicle seat structure. The structure includes a fixedsupport bracket which comprises plate members 10 and 12, which arefastened together and spaced apart by suitable fastening means 14. Theseatback support member 15 is comprised of upper portion 16, which isadapted for mounting to the vehicle seatback, and lower portion 18 whichis rigidly connected by fasteners 20 to upper portion 16. Lower portion18 is mounted for movement between plates 10 and 12 by a pin, showngenerally at 22. The pin 22 has an end portion 24 which is insertedthrough opening 28, through the lower portion 18 of member 15 and intoan opening 26 in the plate 12. In addition, pin 22 has a shoulderportion 30 and slotted portion 32. Slotted portion 32 is adapted toreceive springs 34 and 36 which coact with post 38, mounted on lowerportion 18, to bias seatback support member 15 toward an uprightposition.

The lower portion 18 of the seatback support member 15 has an arcuateperipheral section 40, which is generally concentric with the axis ofpin 22 and which has teeth disposed thereon. These teeth are engaged bymatching teeth on the pawl 42, which serves to lock the seatback supportmember 15 in an adjusted position. The pawl 42 is pivotally mountedbetween the plates 10 and 12 by a pivot pin 44. A gear view slot 45 isprovided in the plate 10 to allow for visual observation of teethengagement during assembly.

Operation of the mechanism which engages pawl 42 with the teeth onperipheral section 40 is best understood by reference to FIG. 1b whichis a sectional side view of the device shown in FIG. 1a depicting theinternal components. The actuating mechanism which moves pawl 42 intothe locking and unlocking positions includes a cam 46, a spring 48, aconnecting rod 50, and an operator 52. In FIG. 1b, cam 46 is shownholding pawl 42 in the locking position (i.e., the teeth of pawl 42 areengaged with the teeth on lower portion 18 of seatback support member15). The cam 46, which is pivotally mounted between the plates 10 and 12by a pivot pin 54, has a first cam arm 56 which engages the pawl 42 tomove and hold the pawl 42 in this position. Cam 46 is biased by spring48, through which connecting rod 50 is placed, in a counterclockwisedirection (as shown in FIG. 1b), to ensure that pawl 42 returns to andremains in a locking position when the angle of the seatback supportmember 15 is not being adjusted. In the configuration shown in FIG. 1a,spring 48 is positioned around connecting rod 50 and rests partially ina slot formed by openings 58 and 60 of the plates 10 and 12,respectively. At the end of the connecting rod 50 near cam 46, spring 48is retained by clip 62, as shown in FIG. 1b, which is attached toconnecting rod 50. At the other end of connecting rod 50 spring 48 isretained by clip 64 which is held in place by plates 10 and 12 andspecifically held in place at one end of the openings 58 and 60 asshown. Thus, when a pulling force is applied to connecting rod 50, cam46 is rotated in a clockwise direction to disengage first cam arm 56from pawl 42 to allow movement of pawl 42 to the unlocking position. Cam46 has a second cam arm 66 which engages pawl 42 at point 68 forpositive displacement to the unlocking position. When a pulling force isso applied spring 48 is compressed between clip 62 which moves with theconnecting rod 50, and between clip 64 which remains stationary. Uponrelease, spring 48 urges, through mechanical interaction, the pawl 42back into a locking position.

The radial spacing of cam arms 56 and 66 can be selected to reduce, orincrease, the amount of rotational movement of the cam 46 which isrequired to move the pawl 42 from the locking to the unlocking position.For example, if cam arm 66 is moved closer (in the clockwise direction)to cam arm 56, the distance from cam arm 66 to pawl 42, when pawl 42 isin the locking position, will be decreased. Then upon rotation of cam46, cam arm 66 will contact pawl 42 sooner and pawl 42 will be urgedinto the unlocking position with less required rotation of cam 46 and,correspondingly, less rotation of operator 52.

Referring again to FIG. 1a, one end of connecting rod 50 is attached tocam 46 to provide for application of a pulling force to cam 46, causingit to rotate in a clockwise direction (as viewed in FIG. 1b). The otherend of connecting rod 50 is attached to operator 52 which is pivotallymounted between plates 10 and 12 by a pin 72 at a point which is nearthe end of elongated portion 70 of plates 10 and 12. An end of pivot pin72 is suitably shaped to receive an operating handle or lever 74 toallow for rotational movement of operator 52 and, via connecting rod 50,cam 46.

There are several problems associated with hinge fittings constructed asshown in FIGS. 1a and 1b. First, placement of spring 48 in the positionshown in FIG. 1b makes the spring itself exposed and unprotected fromcontact with other parts of the reclining seat, or from contact with anindividual using the seat. An exposed spring often has sharp edges atits termination points and any problems associated with the exposedspring are compounded because the spring is moved back and forth everytime the angle of seat inclination is adjusted. This motion can lead totearing of the associated reclining seat or it can cause injury to theuser who must place his or her hands near spring 48 when adjusting theseat by turning lever 74.

FIG. 2 depicts another prior art hinge fitting. The device shown inthese figures is similar to that shown in FIGS. 1a and 1b. Forsimplicity, those elements which are common to the devices of FIGS. 1and 2 retain the same numerical description. Elements of FIG. 2 notpresent in FIG. 1 are primarily those of the linkage which connects thecam 56 to the lever 74. Specifically, referring to FIG. 2, cam 56 isformed with a cam tab 76 which engages a link 78 at a socket 80. Thelink 78 is formed as an elongated planar connector which fits inbetween, and parallel to, the plates 10 and 12. At the opposite end ofthe link 78, a socket 82 is used to attach the link 78 to a tab 84formed as part of the operator 86. To properly bias the pawl 42 into alocking position, a spring 88 can be placed as shown over one end ofpivot pin 72 and held in place so that rotation of lever 74 in aclockwise direction increases the tension on the spring 88. As with thedevice shown in FIG. 1a and 1b, the spring 88 of FIG. 2 is exposed tothe seat and to the user during operation, creating a potential hazard.This and other problems with the prior art have been successfullyovercome as will be explained in greater detail below in conjunctionwith FIGS. 3-8.

In FIG. 3, there is shown a preferred embodiment of a hinge fitting inaccordance with the present invention. The structure includes a fixedsupport bracket comprised of plate members 100 and 102 which arefastened together in a spaced-apart configuration by several fasteners104. A seatback support member 106 also has an upper portion 108 and alower portion 110 which are connected together by fastener 112 and apost 114. As with other hinge fittings, the support member 106 ismounted for movement by a pin 116 which interacts with a spring 118 andthe post 114 to bias the support member 106. The lower portion 110contains an arcuate aperture 130 through which a limiting pin 132passes. As will be discussed later, limiting pin 132 may be mountedbetween plates 100 and 102 in either an aperture formed by openings 134and 135, or an aperture formed by openings 136 and 137. However, whethermounted in either of these apertures, the axis of the pin 132 will beplaced at a point which lies along the centerline of the arc transcribedby the arcuate aperture 130 as the seatback support member 106 isrotated.

Teeth disposed upon a pawl 120, held in place by a pivot pin 126, matewith teeth disposed on the arcuate peripheral section 122 of lowerportion 110 to lock the support member 106 in an adjusted position. Theactuating mechanism which engages pawl 120 with section 122 includes acam 124 held in place between plates 100 and 102 by a pivot pin 128. Cam124 is attached by a pin 138 to a connecting rod 140 which in turn isconnected to an operator 142 by a pin 145. A pivot pin 144 is used tohold the operator 142 in place relative to plates 100 and 102, and toapply torque from the lever 146 to the operator 142.

Formed as part of connecting rod 140, near the end which is attached tothe operator 142, is a hook 148 for accepting an end of biasing spring150 which is bent into a corresponding hook 152. The other end of spring150 is also bent into a hook 154 and is attached to a corresponding hook156 formed as part of plate 100. Also formed as part of plate 100 is aprotective hood 158 which, upon assembly, surrounds spring 150 andprotects against external contact. Alternatively, the hood 158 may notbe formed as part of plate 100 but rather made and attached as aseparate component. Arcuate apertures 160, 162 and 164 are formed inplate 100 and apertures 163 and 165 are formed in plate 102. Theseapertures serve functions which will be described in more detail inconjunction with FIGS. 4-7.

FIGS. 4 and 5 show a side sectional view and a bottom view,respectively, of the preferred embodiment of a hinge fitting. Referringto FIG. 4 which depicts the hinge fitting as if plate 100 was removed,spring 150 is shown in its relaxed position while the reclining seat isin a locking position. As shown, spring hooks 152 and 154 are attachedto the pre-formed connecting rod hook 148 and pre-formed plate hook 156,shown in phantom, of the plate 100. Referring to FIG. 5, it can bereadily seen that no sharp edges nor moving parts of spring 150 areoutwardly exposed during operation of the seatback support member.Specifically, most of the spring 150, including the end hook 154, isshielded by protective hood 158. Further, the distal portion of the hookend 156 of spring 150 is placed to extend inward towards the fixed platestructure 102 to prevent exposure which could cause damage to the seatstructure or injury to a user.

As shown in FIG. 4, when plates 100 and 102 are fastened together,arcuate openings 160 and 163 are placed in alignment as are arcuateopenings 164 and 165. The alignment of these pairs of openings form twoarcuate slots which allow free movement of the connecting rod linkageassembly. Specifically, the arc transcribed by the pin 145 duringoperation of the hinge fitting coincides with the centerline of thearcuate slot formed by the openings 160 and 163. Similarly, the arctranscribed by the pin 138 coincides with the centerline of the arcuateslot formed by openings 164 and 165. When a torque is applied in aclockwise direction to operator 42 in order to urge connecting rod 140so that spring 150 is expanded, there will be some lateral displacementat the respective ends of the connecting rod where pins 138 and 145 areattached. In previous hinge fittings, this displacement at the pinconnection points caused contact with the interior side walls of plates100 and 102 which in turn had the potential for eventually causingfailure of the pin and the linkage assembly. Forming plates 100 and 102with the openings 160, 163, 164 and 165 as shown enables the pins 138and 145 to travel through their entire range of motion withoutcontacting either of the plates 100 and 102.

An additional aspect of the present invention that pertains to the lockactuating mechanism will be discussed by reference to both FIGS. 4 and6. FIG. 6 shows an enlarged view of the engagement area between a firstcam arm 170 and the pawl 120 when the pawl 120 is in the lockingposition. Application of force to the seatback support member 108 cancause pawl 120 to transmit a force, represented in FIG. 6 by arrow F, tocam 124. Force F acts perpendicularly to the point of contact betweencam 124 and pawl 120. To ensure that force F does not move pawl 120toward the unlocking position, a camming surface 174 is shaped such thatforce F imparts a movement of rotation to cam 124 that tends to rotatecam 124 in the counter-clockwise direction (as viewed in FIG. 6). Thisin turn tends to urge pawl 120 toward the locking position as thecamming surface 174 is in contact with a pawl locking surface 188 inresponse to the application force F. For this to occur, force F must lieon a line which passes above the center of pivot pin 128, as viewed inFIG. 4. A camming surface shape which facilitates this result is onethat is parabolic. With this shape, the radius of curvature of surface174 constantly increases as measured from point 176 to point 178 withrespect to the center of pivot pin 128. Thus, as pawl 120 is moved intothe locking position, the line of action of force F is more quicklybrought into a position which lies above the center line of pivot pin128 to produce the anti-unlocking effect described above.

To ensure that the cam 124 and the pawl 120 are in the correctpositional arrangement to properly direct force F, alignment markings180 and 182 are found on cam 124 and pawl 120, respectively.Specifically, alignment marking 180 is placed on an outwardly facingsurface 184, which is perpendicular to camming surface 174, of the camarm 170, and alignment marking 182 is placed on an outwardly facingsurface 186, which is perpendicular to the locking surface 188, of thepawl 120. As shown in FIG. 6, alignment marking 180 extendssubstantially to and, desirably all the way to, an edge of cam arm 170formed by the intersection of the surfaces 184 and 174. Likewise,alignment marking 182 extends substantially to an edge of pawl 120formed by the intersection of the surfaces 186 and 188. Desirably, thealignment markings are positioned such that whenever the stackedtolerances are such that the hinge fitting will remain locked despite agiven torque load, the alignment marking 180 on the surface 186 of thepawl 120 is to the left of the alignment marking 180 on the surface 184of the cam arm 170. The precise alignment will vary due to variations inthe size and shape of the cam and pawl, as well as for other reasons.

In contrast to prior hinge fittings, the alignment marks are positioneddirectly on the cam and pawl, rather than the pawl and housing, therebygiving a more reliable indication of whether the camming surface 174 ofthe cam 170 and the locking surface 180 of the pawl 120 are positionedrelative one another such that they will maintain the locking engagementof the hinge fitting.

Importantly, since the alignment markings extend substantially to theedge, between surfaces 184 and 174 and between 186 and 188,respectively, of their respective components, no guess-work is requiredby the worker assembling the unit to determine whether the fitting iswithin acceptable tolerances. That is, if the alignment marking on thepawl is to the left (as shown in FIG. 6) of the alignment marking on thecam, force F will be properly directed above the center line of pivotpin 128 thereby ensuring that the force actually urges the cam moreforcefully into engagement with the pawl.

The relative position of these alignment markings can be viewed once theinternal components of the fitting are assembled, but before thesandwich plates are attached together. Desirably, a view window 161 isformed as part of plate 100 which will also allow easy verification ofalignment after both plates are assembled.

A final feature of the present invention can be seen with reference toFIGS. 7 and 8. FIGS. 7 and 8 are side views of the present inventionthat depict the internal components of the fixed apparatus. In thecommercial market, it is typically desired that adjustable hingefittings have a certain maximum rearwardly inclined position. As aresult, hinge fittings are typically manufactured to allow a singlepredetermined maximum inclined position. Currently, in the commercialmarket for hinge fittings there are a finite number of desired maximumreclining levels. Because of this, manufacturers usually design andconstruct several separate hinge fittings each tailored to a specificcustomer's needs. Manufacturing a separate hinge fitting for eachspecific need can be very costly and may take longer than a customer iswilling to wait. Two maximum reclining levels for seats which arecommonly desired are for those which recline to 30 degrees and 45degrees from the vertical resting position.

A hinge fitting which can be universally manufactured but laterconfigured for several applications is therefore highly desirable. InFIGS. 7 and 8 there is shown, in accordance with the present invention,a seatback support member which is uniquely manufactured to accommodatetwo separate maximum reclining levels. FIG. 7 shows a seatback supportmember having plates 100 and 102 that are formed with two circularapertures. One circular aperture is formed by alignment of openings 134and 135, and the second circular aperture is formed by alignment ofopenings 136 and 137. A pin is placed in either of these apertures,depending upon which maximum reclining level is desired.

FIG. 7 shows a seatback support member configured with a pin 132 placedin aperture formed by opening 134 and 135. The pin 132 passes througharcuate aperture 130 of seatback support portion 110. The pin 132 ismanufactured to have a diameter slightly less than the width of arcuateaperture 130 in order to fit through aperture 130 without interferingwith the operation of the seatback support member 108. Placement of thepin 132 is such that the axis of the pin is positioned at a point alongthe centerline of the arc transcribed by aperture 130. Seatback supportmember 108 is thus allowed to rotate about pivot pin 116 to a point atwhich the pin 132 abuts lower portion 110 at the end of the arcuateaperture 130. As shown in FIG. 7, this allows seatback support member torecline to a level of about 45 degrees.

Both circular apertures formed by openings 134-137 are placed at pointscoincident to an arc transcribed with a center located at the pivot pin116. In order to obtain a maximum reclining level of only 30 degrees,pin 132 may be positioned in the circular aperture formed by alignmentof openings 136 and 137 as shown in FIG. 8. In this position, the pin132 will abut lower portion 110 at the end of the arcuate aperture 130sooner during clockwise rotation of seatback support member 108.Manufacturing only one type of hinge fitting which may be configured inmultiple ways is economically superior to manufacturing multiple hingefittings for various needs. The particular twin-configuration hingefitting depicted in FIGS. 7 and 8 is, of course, only exemplary. Thissame design could be used for producing a hinge fitting with three ormore possible configurations having a variety of maximum recliningpositions.

From the preceding description of the preferred embodiments, it isevident that the objects of the invention are attained. Although theinvention has been described and illustrated in detail, it is to beclearly understood that the same is by way of illustration and exampleonly and is not to be taken by way of limitation. The spirit and scopeof the invention are to be limited only by the terms of the appendedclaims.

I claim:
 1. A hinge fitting for a reclining vehicle seat structure,comprising:a fixed support assembly comprising a pair of sandwichbracket plates; a seatback support assembly pivotally connected to saidfixed support assembly by a first pivot assembly, said seatback supportassembly being movable from an upright position, rearwardly through arange of rearwardly inclined positions; a rotatable locking memberpositioned at least partially between said bracket plates, pivotallyconnected to said fixed support assembly by a second pivot assembly,said second pivot assembly fixing said seatback support assembly inadjusted positions throughout the range of rearwardly inclinedpositions, said locking member defining a first face and firstengagement surface, said first face and said first engagement surfacebeing generally perpendicular to one another and intersecting along afirst edge, said first face of said locking member defining a firstalignment marking extending substantially to said first edge; a lockactuator assembly, said lock actuator assembly including a rotatable campivotally connected to said fixed support assembly by a third pivotassembly, said cam defining a second face and a second engagementsurface, said second face and said second engagement surface beinggenerally perpendicular to each another and intersecting along a secondedge, said second face of said cam defining a second alignment markingextending substantially to said second edge, said second engagementsurface engageable with said locking member to cam said locking memberinto said locking position and engaging said locking member at anengagement point when said locking member is in said locking position;wherein said locking member and said cam are sized and shaped such thatwhen said first alignment marking is positioned to a predetermined sideof said second alignment marking said engagement point is located suchthat a force acting perpendicularly at said engagement point urges saidcam into engagement with said locking member, thereby preventingmovement of said locking member out of said locking position in responseto forces applied to said seatback support member.
 2. A hinge fittingfor a reclining vehicle seat as described in claim 1 wherein one of saidpair of sandwich bracket plates defines an aperture and wherein saidalignment markings are positioned in said aperture formed in saidsandwich bracket plate when said lock actuator assembly is in a lockingposition for viewing the relational position of said first and saidsecond alignment markings.
 3. A hinge fitting for a reclining vehicleseat as described in claim 1 wherein said cam is biased by a springtoward said locking position.
 4. A hinge fitting for a reclining vehicleseat as described in claim 1 wherein said lock actuator assemblyincludes a fourth pivot assembly connected to one of said sandwichbracket plates and operatively linked to said cam for transferring arotational force to rotate said cam.
 5. A hinge fitting for a recliningvehicle seat as described in claim 4 wherein said fourth pivot assemblyis linked to said cam through a link which is pivotally attached to saidfourth pivot assembly by a first connecting pin and pivotally attachedto said cam by a second connecting pin.
 6. A hinge fitting for areclining vehicle seat as described in claim 5 wherein one of saidsandwich bracket plates is formed with an aperture positioned and shapedsuch that it exposes one of said connecting pins throughout saidconnecting pin's entire range of motion thereby preventing saidconnecting pin from contacting said sandwich bracket plate.